Method of Phase Compensation for Holographic Data Storage

概要

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The characteristics of holographic recording in the presence of phase noise caused by air disturbances and vibrations were studied. Diffraction efficiencies were calculated by a finite-difference time-domain method. Simulation results showed that the amplitudes of fringes decrease with increasing phase noise level, and thus, diffraction efficiencies decrease. A novel method of phase compensation for holographic data storage was proposed. Interference fringes were impinged on a charge-coupled device (CCD) camera symmetrically positioned relative to a recording medium, and the fringes in the medium were estimated using the fringes on the camera. Phase information was obtained by fast Fourier transform, and a phase modulator was set in the reference path and driven to reduce the phase error, so that the phase on the camera was stabilized. By this method, the standard deviation of the phase error was reduced to less than 1/10 that obtained by a conventional method. The diffraction efficiencies of angle-multiplexing in a photopolymer were measured and the relative multiplexing number with feedback control was 50% larger than that without it. As the holographic data storage device records the phase, the proposed method is an important and feasible technology.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2007-06-30